This invention relates to detergent compositions incorporating internal vicinal disulfates as the, or one of the surfactants.
In the constant search to improve organic detergent products, surfactants have been sought which have a combination of features such as detergency, sudsing, solubility, soil suspension, etc. that are independent of each other and hence would provide the greatest flexibility in formulation. Although there are a number of surfactants which approach this ideal, a satisfactory balance of properties is often difficult to achieve as they are mutually exclusive. In particular, a balance between sudsing and detergency has been found to be difficult to realize in a single surfactant.
Low sudsing is a highly desirable property for a surfactant intended for use in automatic dishwashing detergents. This characteristic is a feature of a large number of nonionic surfactants but is not possessed by many anionic materials. Additionally, anionic surfactants having satisfactory detergency characteristics generally display relatively high sudsing properites under the same conditions.
Alkyl disulfates as a broad class of compounds are known in the detergent art. For example, U.S. Pat. No. 3,714,076, Jan. 30, 1973, and U.S. Pat. No. 3,634,269, Jan. 11, 1972, both to R. G. Anderson, disclose 1,2-, 1,3-, and 1,4-disulfate surfactants. In addition, internal disulfates of non-vicinal variety are disclosed in U.S. Pat. No. 3,686,098, Aug. 22, 1972, to Ira Weils, where their general utility is stated to be as a laundry aid in phosphate-free detergents. Vicinal alkane diols themselves are disclosed in U.S. Pat. No. 3,775,300, issued Nov. 27, 1973, to Heimold Batha as components of detergent compositions useful for automatic dishwashing.
There appears, however, to have been no appreciation prior to the present invention that certain internal vicinal disulfates are low-foaming, hardness insensitive surfactant detergents which are particularly useful combined with polyethoxylated nonionic surfactant detergents. That they are low-foaming surfactants was quite unexpected since anionic surfactants such as higher molecular weight alkyl sulfates, alkyl sulfonates, or arylalkyl sulfonates are not known to exhibit low-foaming surface activity; and prior disulfates, likewise, are not known to exhibit low-foaming and surface activity.